Using the PO4 test reference solution

Question:

ive recently got one of your new style phosphate test kits and wanted to check its acuracy with the included reference fluid but i dont see the exact method of doing this explained in the instructions ,the test quotes there is enough fluid for 5 tests so does that mean you are supposed to fill just one tube and match by eye ? or are you meant to use the comparator with the other tube and if so what water should be used for that ?
thanks lee

Answer:

Lee
You are supposed to use the reference solution instead of the tank water and conduct the test in the normal manner.

This allows you to check the test against a known phosphate level printed on the bottle.

Have you visited our website and followed the links to watch the videos for each test.

Cheers
Stuart

Customer response:

hi Stuart
thanks for the quick response ,yes ive watched the video and understand the test kit ,my point is that the reference solution is 0.08 po4 which means using the low range test and 12ml of water in each tube for each test so 1 test will use 24ml of water, so if your saying im supposed to use the refererence solution as i would tank water then it will last for 2 tests ? as the bottle is 60ml where as the test kit says there is enough for 5 reference tests ?
thanks lee

D-D Repsonse:

Hi Lee

Just to pick up on this, when using the reference test please fill the colour reference tube with RO water.

Whilst we ask to fill both tubes with sea water during standard testing there isn’t a requirement to fill both

tubes with reference solution.

The reason for using tank water in both tubes during normal testing is that there maybe some yellowing or

turbidity within the tank water that may bias the visual accuracy when comparing the two tubes.

This isn’t an issue with the reference solution so RO water can be used in the other tube.

Hope this helps Tony

Response:

hi Tony
thanks for the follow up message, that works fine
could you also tell me if i can use this test kit to check my ro water ? as im trying to track down the source of phosphate problem , or does it work with salt water only ?
thanks lee

D-D response:

Hi Lee

Testing RO water can give odd results due to the fact that it is so ionically pure. Many test kits rely on the sample being within

certain Ph ranges, this includes the PO4 kit. The Ph of RO water sits around neutral i.e 7 but more importantly the water has no buffering system so any small changes to the water from dissolved CO2 etc. can cause the Ph. to swing(low with dissolved CO2).

This means that the reagents used to test can upset the Ph. of the water and push it outside of the expected Ph. that the kit is designed for. Even electronic test such as Ph. probes do not work as they come to a Ph. result by measuring the Hydrogen cation value of the water.

As buffer system is non existent the probe will report back with sporadic and inaccurate results.

What i suggest you do is to test the TDS of the RO water as a TDS meter is designed to read the total anion/cation value of the RO water.

If you have a TDS reading then you will need to either use a high quality Di resin to bring this down to 0 and possible look to renew all pre filters and membrane if the Di is exhausted very quickly due to high TDS pre resin/post membrane.

You may find the following the link interesting:

http://www.theaquariumsolution.com/tds-what-does-it-mean-and-why-should-i-test

Hope this helps

Tony